In a heat exchanger, an intercooler is an apparatus for cooling compressed air at a high temperature and a high pressure by a supercharger to increase an output of an engine.
The air rapidly compressed by the supercharger becomes extremely high in temperature and thus a volume of the compressed air is expanded and an oxygen density reduces, resulting in a reduction in charging efficiency in the cylinder. Therefore, the intercooler cools the high-temperature air compressed by the supercharger to increase suction efficiency of the engine cylinder and increase combustion efficiency, thereby increasing fuel efficiency.
The intercooler in charge of the role may be divided into water-cooled type and air-cooled type according to a cooling method. Among those, a principle of a water-cooled intercooler 10 is similar to that of an air-cooled intercooler, but the water-cooled intercooler 10 differs from the air-cooled intercooler in that it cools the compressed air using cooling water of a vehicle, water or the like instead of using external air when cooling the intercooler through which the high-temperature air passes.
The water-cooled intercooler 10 illustrated in FIG. 1 includes a first header tank 20 and a second header tank 30 disposed in parallel while being spaced apart from each other by a predetermined distance; a first inlet pipe 40 formed in the first header tank 20 and having air introduced therethrough and a first outlet pipe 50 formed in a second header tank 30 and having the air discharged therethrough; a plurality of tubes 60 having both ends fixed to the first header tank 20 and the second header tank 30 to form air passages; fins 70 interposed between the tubes 60; a cover member 80 having an assembly of the tubes 60 and the fins 70 housed therein and opened on one side surface and the other side surface where one end part of the tube 60 is located; and a second inlet pipe 41 formed on one side surface of the cover member 80 and having cooling water introduced therethrough and a second outlet pipe 51 formed on one side of the cover member 80 and having the cooling water discharged therethrough.
On the contrary, the water-cooled intercooler 10 may be configured to pass cooling water through an inside of a tube and include a case having a heat exchanger core disposed therein and surrounding the core, with the heat exchanger core being an assembly in which a header tank, a tube, and a fin are assembled, and be cooled by the core while air passing through the inside of the case.
However, in order to increase the heat exchange efficiency, the water-cooled intercooler is surrounded with the case so that air does not bypass the core. Since there are inlet/outlet header tanks which are spaces in which the cooling water stored in the core disposed in the case is distributed into the tubes and flows, the heat exchange performance may deteriorate. Also, when air does not pass through a part where the header tanks of the core are disposed, a pressure drop amount of air increases and thus a pressure loss may increase.
In addition, on the contrary, the water-cooled intercooler 10 may be configured to pass cooling water through an inside of a tube and include a housing having a heat exchanger core disposed therein and surrounding the core, with the heat exchanger core being an assembly in which a header tank, a tube, and a fin are assembled, and cool air by the core while air passing through the inside of the housing. The water-cooled intercooler may include a top plate joined to an upper surface of the heat exchanger core for strength reinforcement, in which the top plate is formed in a flange shape and may be joined to an opening portion of the housing, in which the heat exchanger core is housed, by a fastening means or the like.
However, since as the high-temperature air compressed by the supercharger passes through the inside of the housing, the top plate joined to the heat exchanger core is deformed by the pressure of the air and thus a clearance is formed between the contact surfaces of the housing and the top plate, such that air may be leaked to the outside of the housing.
In addition, the conventional heat exchanger has a low mechanical strength, and therefore to reinforce the mechanical strength, the conventional heat exchanger may be configured to increase structural rigidity by joining a plate for strength reinforcement to an upper side surface on which the tank portion 10 is formed and a lower side surface opposite thereto.
However, if the plates for strength reinforcement are separately formed on the heat exchanger and joined to each other for the strength reinforcement, the number of components to be assembled and joined increases, such that assembling performance and productivity may be reduced.